SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '303566bc6e68e5eb3870103565235572e53e347c66fdd7f03b6c038985649fbd' 
  AND token = 'nHkwEqvWun+BDnA7ZurKNxnGlvNtnB6OdKPPrk+F1YI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}